package org.apache.lucene.search.spans;
/**
* Copyright 2006 The Apache Software Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import java.io.IOException;
import org.apache.lucene.search.Weight;
import org.apache.lucene.search.Scorer;
import org.apache.lucene.search.Explanation;
import org.apache.lucene.search.Similarity;
class SpanScorer extends Scorer {
private Spans spans;
private Weight weight;
private byte[] norms;
private float value;
private boolean firstTime = true;
private boolean more = true;
private int doc;
private float freq;
SpanScorer(Spans spans, Weight weight, Similarity similarity, byte[] norms)
throws IOException {
super(similarity);
this.spans = spans;
this.norms = norms;
this.weight = weight;
this.value = weight.getValue();
doc = -1;
}
public boolean next() throws IOException {
if (firstTime) {
more = spans.next();
firstTime = false;
}
return setFreqCurrentDoc();
}
public boolean skipTo(int target) throws IOException {
if (firstTime) {
more = spans.skipTo(target);
firstTime = false;
}
if (! more) {
return false;
}
if (spans.doc() < target) { // setFreqCurrentDoc() leaves spans.doc() ahead
more = spans.skipTo(target);
}
return setFreqCurrentDoc();
}
private boolean setFreqCurrentDoc() throws IOException {
if (! more) {
return false;
}
doc = spans.doc();
freq = 0.0f;
while (more && doc == spans.doc()) {
int matchLength = spans.end() - spans.start();
freq += getSimilarity().sloppyFreq(matchLength);
more = spans.next();
}
return more || (freq != 0);
}
public int doc() { return doc; }
public float score() throws IOException {
float raw = getSimilarity().tf(freq) * value; // raw score
return raw * Similarity.decodeNorm(norms[doc]); // normalize
}
public Explanation explain(final int doc) throws IOException {
Explanation tfExplanation = new Explanation();
skipTo(doc);
float phraseFreq = (doc() == doc) ? freq : 0.0f;
tfExplanation.setValue(getSimilarity().tf(phraseFreq));
tfExplanation.setDescription("tf(phraseFreq=" + phraseFreq + ")");
return tfExplanation;
}
}
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